Rails 3 - can't install pg gem

Question

When I try to run bundle (bundle install), I all the time get

Installing pg (0.13.2) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /Users/ryan/.rvm/rubies/ruby-1.9.2-p290/bin/ruby extconf.rb 
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/Users/ryan/.rvm/rubies/ruby-1.9.2-p290/bin/ruby
    --with-pg
    --without-pg
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config


Gem files will remain installed in /Users/ryan/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.13.2 for inspection.
Results logged to /Users/ryan/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.13.2/ext/gem_make.out
An error occured while installing pg (0.13.2), and Bundler cannot continue.
Make sure that `gem install pg -v '0.13.2'` succeeds before bundling.

I use Mac OS X 10.6, the version of installed PostgreSQL is 9.1. I found the problem is in the libpq-dev, how could I install/fix that?

Answer 1

if you are running on Linux you may be interested in what worked for me:

sudo apt-get install postgresql
sudo apt-get install libpq-dev

Then

gem install pg

then

bundle install

src: http://wikimatze.de/installing-postgresql-gem-under-ubuntu-and-mac

Answer 2

As stated in your error log you need to pass in the path to the pg_config. Try to install the gem using:

gem install pg -- --with-pg-config= 'PATH_TO_YOUR_PG_CONFIG'

If you are not sure where your pg_config is, and assuming you are on Linux or Mac, you can run the following command:

which pg_config

Your pg-config can be in different locations depending on how you installed postgres.

Answer 3

If you're using Postgress.app then youll want access to its command-line tools. Enter the following line in your terminal or your PATH profile:

 PATH="/Applications/Postgres.app/Contents/MacOS/bin:$PATH"

gem install pg should now work. (This is what worked for me.)

Note New versions path looks like:

/Applications/Postgres.app/Contents/Versions/<version>/bin